Method of treating unstable cracked hydrocarbons



Patented May 8, 1951 METHOD OF TREATING UN STABLE CRACKED DROCARBONS' Barney R. Strickland and Byron M.,Vanderbilt,

Westfield, N. J., assigncrs to StandardpilDevclopment Company, a corporation of Delaware- Application September 11, 1948, SerialNo. 48,884

Claims.

The present invention is concerned with the removal of unsatisfactory constituents from hydrocarbon mixtures. The invention is more specifically concerned with the removal of gum forming poly olefins and similar compounds from hydrocarbon mixtures, which compounds tend to form varnish in an internalcombustion engine. The invention is especially directed toward the production of aromatic fractions and motor fuel fractions substantially, free of undesirable conjugated diolefins and; certain non-conjugated- In accordance with the processof :thepresent hydrocarbon mixtures in the presence of-a peroxide catalyst, subjecting the emulsion toa heat' treatment and then segregating the treated-fraction.

It is well known in the art to treat hydrocarbon fractionsboiling in the motor fuel boiling-range in order to remove certain'olefinic type-constituents such asconjugated diolefins. Forexample,

in the manufacture of a high quality-"gasoline from cracked stocks, it is necessary to remove cer-' tain of these conjugated diolefins in order to pro'-" duce a product that will not form varnish when employed in an internal combustion engine; If

these constituents are not removed they polymerizeone with the other and with =other*'un" stable constituents to form gummy-compounds; For instance, cyclopentadiene has beenfound "to be varnishforming. Also in many processes it is desirable to segregate fractions which have a relatively high aromatic content. In operations of this, character it is rather diflicult to separate the conjugated diolefins ofsimilar boiling range from the aromatic constituents. Heretofore;various methods have been utilized in the vartin order to remove the conjugated diolefinsfrom hydrocarbon mixtures. is to use clay treating operations: While operations of this character have been successful some of the aromatic constituents are lost due to the fact that these aromatic constituents .poly- One method for example,

merize with the diolefins. The segregation of fractions having a high aromatic content is particularly difiicult when treating certain fractions, such as fractions boiling in the gasoline boiling range which have been produced by steam cracking operations. A typical steam cracking operation is to treat a naphtha boiling in the range from about 200 F. to 400 F. at atmospheric pressure and at a temperature. intherange, from-- about;1200 F; to 1400 F. Under these conditione the concentrationof the conjugated: diolefins' inthe ifinal'product may range'from about'l0% to 15%.

As pointed out heretofore, certain 'naphthas boiling-in the gasoline boiling range tendto formgummy constituents and varnish in airinte'rnal' combustion. engine; This is particularly :thecase when the'naphthas are cracked naphthas result ing from .steam cracking operations. 1 1

In accordance with the present inventiongan improved product is secured by"emulsifying 'thar hydrocarbon mixtures. containingundesirable constituents such as. conjugated diolefins in which the double bonds are attached to' terminal csrba atoms. The emulsionis then heated Wherebythe gum forming constituents rapidly form 1 gummy substances; These gummy substances are segregated from the treated product.

Inaccordancetwith the present process; the gum forming process isaccelerated'by the heating of the emulsion comprising the crac-ked*-* naphtha containingobjectionable conjugated and non-conjugated:diolefins.-- The objectionable 0on stituents comprise conjugated die'nesycertain polyenes having three or more double bonds} ce1"'- tain vinyl'compounds' activated because of structure of s'ubstituent, mercaptans which condense with olefinic bodies, and thelike. It is to be"? understood that all of the conjugated dienesdo not contribute to gasoline instability resulting'in the formation of varnish. The present invention" may be readily understood by-reference to the" drawings illustrating embodiments of the same. Figure 1 illustrates an adaptationfof thepresent invention wherein theemulsion is'broken by meansof a suitable reagent. Figure '2 illustrates an embodiment of the invention wherein the product is removed from the emulsion, preferably" by a steam distilling operation and the emulsion recycled- Referring specifically to Figure 1, a feed stream, which for this purpose is assumed to. be a heavy naphthaboiling in the range from about 206 400 F., is introduced into 'cracking. zone- H!- by means of line I. Temperature and pressure conditions in cracking zone In may be adjusted, de-

percentof steam is from about 40% to 80%. A gas stream boiling below the motor fuel boiling range is withdrawn from zone It! by means of line 2. Various other streams boiling above the motor fuel boiling range are withdrawn by means of lines 3 and 4. It is to be understood that any number of streams may be segregated and that zone I may comprise any number of desired units. The fraction boiling in the motor fuel boiling range is withdrawn from zone by means of line 5.

In accordance with the present invention, an aqueous mixture comprising an emulsifying agent and a gum forming promoter is introduced into line 5 by means of line 6. For the purpose of illustration it is assumed that a gum forming promoter comprises a peroxide or a peroxide salt. The emulsion is introduced into zone which may be maintained at any suitable temperature. The emulsion is withdrawn from zone 20 by means of line I and introduced into zone wherein the emulsion is broken by suitable means. 1

The aqueous layer is withdrawn from zone 30 by means of line 9 and handled in any manner desirable. The treated gasoline is withdrawn from zone 30 by means of line 8 and introduced into distillation zone 40. Temperature and pressure conditions are adapted to remove overhead, by means of line H, the hydrocarbon fraction boiling in the motor fuel boiling range. The gummy constituents are removed from zone by means of line 12.

Referring specifically to Figure 2, a feed hydrocarbon stream is introduced into thermal cracking zone by means of line 5 l. The gas fraction is withdrawn overhead from zone 53 by means of line 53, while various side streams are withdrawn by means of lines 54 and 55. A hydrocarbon fraction boiling in the motor fuel boiling range is withdrawn from zone 50 by means of line 56 and mixed with an aqueous mixture comprising an emulsifying agent and a catalyst promoting agent which is introduced by means of line 51. The mixture is introduced into zone 69 wherein the emulsion may be maintained at any desired temperature or pressure for any desired length of time with suitable agitation. The emulsion is withdrawn from zone 60 by means of line 5! and introduced into zone iii. In accordance with this adaptation of the invention, steam is introduced into zone 70 by means of line 62 under temperature and pressure conditions to remove overhead from zone In by means of line 63 a hydrocarbon fraction boiling in the motor fuel boiling range. The emulsion containing the polymerized and condensed materials is removed from zone 10 by means of line 54 and may be recycled in whole or in part and introduced into line 56. However, in general it is preferred to introduce at least a portion of this emulsion into zone 88 by means of line 65 wherein the high boiling fraction is segregated from the emulsion. The polymerized constituents are withdrawn from zone an by means of line 66 while the emulsion is withdrawn from zone 88 by means of line 6'! and recycled as hereinbefore described. In operation a part of the emulsion in zone 80 is removed from the systemon each pass and fresh emulsifier and peroxide material added.

The present invention may be varied appreciably. As pointed out heretofore, the invention is broadly directed to an improved method of removing gum forming and mercaptan compounds from hydrocarbon fractions containing the same. The invention is especially adapted for the production of high quality gasolines and high quality, relatively pure aromatic fractions which are segregated and produced from cracked hydrocarbons. The concentration of aromatic constituents in the product stream from a steam cracking operation wherein the feed stock boils in the motor fuel boiling range, ranges from 15% to 40% and higher.

Although the process may be adapted for the treatment of hydrocarbon fractions boiling over a wide boiling range, it is especially useful in the removal of gum forming constituents in gasolines. It is, however, to be understood that the process is also adapted generally for the treatment of fractions derived from catalytic cracking, high pressure thermal cracking, reduced crude cracking and the like.

The emulsifying agent may be selected in general from the class of known emulsifying agents. Suitable emulsifying agents are, for example, tallow soap, rosin soap, salts of alkyl-aryl sulfonic acids, salts of alkyl sulfuric acids as those derived from sulfating alcohols containing from 12-18 carbon atoms. Other suitable emulsifying agents are hydroxy polyethers as those derived by condensing several mols of ethylene oxide with one mol of an alcohol or a phenol. Such emulsifiers may be used in the concentration of 0.1-1% based upon the oil being treated.

While any emulsifying agent of the class of emulsifying agents in general may be used, it may be desirable to break the emulsion by allowing the same to settle. In such a case a more soluble emulsifying agent is used, for example, a sodium salt of fatty acids of 8-10 carbon atoms, or a relatively small amount of a more active emulsifier. The presence of an electrolyte, such as sodium chloride, in the system also facilitates layer separation.

The promoting agent likewise may be selected from the general class of peroxides or per-salts. However, in general it has been found that the promoting agent should be selected from the class of inorganic agents as compared to organic polymerizing agents. 6 u i t a b l e polymerizing agents are, for example, potassium persulfate (X28208), sodium perborate (NaBOa-ellzo), and hydrogen peroxide. Organic peroxides such as benzoyl peroxide, cumene hydroperoxide, and tertiary butyl hydroperoxide are also useful. Such promoting agents may be used in a broad range of concentration, but preferably in the range of 0.2-0.8% based on the oil treated. Besides using an oxygen donor, free oxygen or air may be used as the catalyst. Usually, at least some air or pure oxygen is used as the promoting agent. In such a system gas pressures up to 50-200 pounds are used at temperatures from about 122-302 F.

A particularly preferred adaptation of the present invention is to add to the hydrocarbon mixture to be treated an aqueous mixture comprising an emulsifying agent. Also activators are advantageously used to promote the action of the oxygen type catalyst. Such activators include salt of polyvalent metals as those of iron and cobalt, complex metal salts as potassium ferricyam'de, reducing sugars as glucose and the like.

The emulsion zone 20 may comprise any suitable number of units. It is desirable to employ agitation in zone 20. Furthermore, any suitable emulsion breaking agent may be employed, if it is desired to break the emulsion as described with respect to an operation similar to Figure l.

Suitable emulsion breaking agents are, for example, salt brine, sulfuric acid, a water-soluble alcohol, hydrated l-ime,-o r the like. Mechanical means such as centrifuging, passing an electric current at high voltage, allowing to settle in the absence of agitation may also be employed.

The temperature at which the emulsion is heated should be in the range from about 100- 300 F. It is preferred'that'theemulsion be subjected to a temperature in the range of 150- 200 F.

The invention may be further understood by' the following .examplesillustrati-ng embodiments of the same.

Example 1 20.0 parts by weight of a thermally cracked gasoline was mixed with'the following:

360 parts water parts ,tallow soap 0.16 part sodium hydroxide 1.5 parts potassium persulfate 0.4 part potassium ferricyanide This mixture was emulsified by agitation and heated in a closed receptacle for a period of 16 hours at 113 F. The mixture was distilled to remove the gasoline. The distillate was washed with 5% NaOI-I, then by water, inhibited with 5 P. P. M. of U. 0. P. Inhibitor #5 (N,N'- di secondary butyl-p-phenylenediamine) and tested.

Another portion of the identical gasoline was handled as described above, except that it was not emulsified with the treating solution.

The results were as follows:

Copper B k C Total Dish opper Per Cent Gum 1 Down 2 No. Sulfur Untreated- 196 185 5. o 0. 137 Treated 5 315 0. 5 0. 10s

3 Federal Specifications VV-L-79lc, issued May 12, 1945, Method 3 0 ll 2 AS:TMD52546. 3 Oil and Gas Journal, p. 99, July 29, 1937.

Example 2 Additional runs were made similar to those described in Example 1 except that a temperature of 167 F. was employed and the contact time of 1 hour. Results were equally satisfactory.

Ezrample 3 In an example in which 2 parts of sodium perborate was used as the catalyst (NaBO3-4H2O) instead of the persulfate, and the mixture heated at 167 F. for one hour, the gasoline so treated showed an excellent improvement over the untreated material.

copper Break- Peroxide down No Untreated 589 75 1. 9 Treated 3. 5 300 O. 1

-Example 4 300 parts of water 2 parts of tallowsoap 2 parts of Daxad 11 0.75 .part potassium persulfate 0.2 part of potassium ferricyinide 2.0 parts of sodium hydroxide The product so obtained not only had greatly improved gum forming and breakdown characteristics, but unlike the feed stock gave no precipitate when treated with the doctor reagent.

Example 5 A feed stock similar to that described with respect to Example '1 was employed. This feed stock was treated with an equal volume of one per cent sodium rosinate solution containing 0.02% of ferrous sulfate in the presence of one volume of air at pounds gauge pressure.

The results were as follows:

00 per ASTM D i sh Breakfi Gum down 75# Air Pressure plus 0.02%

FeSOlJHzO 2 300 o. 1 Untreated 589 75 l. 9

Having described the invention, it is claimed: 1. Process for the removal of gum forming components of a hydrocarbon fraction which comprises emulsifying said hydrocarbon fraction with water, subjecting the resulting emulsion to an elevated temperature, whereby said gum forming components form higher boiling constituents, then breaking said emulsion and separating an oil phase comprising said hydrocarbon fraction and said higher boiling constituents, thereafter separating said higher boiling constituents from said hydrocarbon fraction whereby the same is rendered substantially completely free of gum forming components.

2. A process as defined in claim 1 wherein said hydrocarbon fraction contains at least 15% aromatic constituents.

3. A process as defined in claim 1 wherein said hydrocarbon fraction is obtained by thermal cracking of petroleum.

4. A process as defined by claim 1 wherein said hydrocarbon fraction contains at least 40% aromatic constituents and from 10-15% conjugated diolefins.

5. Process as defined by claim 1 wherein said elevated temperature is in the range from F. to 200 F.

6. Process for the production of a high quality motor fuel which comprises emulsifying a hydrocarbon fraction boiling in the motor fuel boiling range with water containing a suitable emulsifying agent, adding to the resultant emulsion a catalyst suitable for promoting the conversion of gum forming components contained in said hydrocarbon fraction to higher boiling constituents, subjecting said emulsion to a temperature in the 1 A colloid stabilizer marketed by the Dewey & Almy Company.

range from about 100 F. to 300 F. and thereafter breaking said emulsion whereby an oil phase separates comprising said hydrocarbon fraction and said higher boiling constituents, thereafter separating said higher boiling constituents from said hydrocarbon fraction whereby a motor fuel substantially free of gum forming components is secured.

7. Process as defined by claim 6 wherein said emulsion is heated to a temperature in the range from 150 F. to 200 F.

8. Process as defined by claim 6 wherein said hydrocarbon fraction is derived from a steam cracking operation.

9. Process for the production of a high quality motor fuel which comprises emulsifying a hydrocarbon fraction boiling in the motor fuel boiling range with water containing a suitable emulsifying agent, subjecting the resulting emulsion to an elevated temperature whereby gum-forming components form higher boiling constituents, steam treating said emulsion to remove overhead said hydrocarbon fraction boiling in the motor fuel boiling range, separating the bottoms containing said higher boiling constituents and recycling at least a portion of the bottoms to further contact additional hydrocarbon fractions boiling in the motor fuel boiling range.

8 10. Process as defined by claim 9 wherein said higher boiling constituents are at least partially removed from said bottoms prior to recycling said bottoms to further contact additional hydrocarbon fractions.

BARNEY R. SI'RICKLAND. BYRON M. VANDERBILT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 901,718 Ludecke Oct. 20, 1908 1,041,604 Dehnst Oct. 15, 1912 1,677,425 Axtell July 1'7, 1928 1,772,921 Tausz Aug. 12, 1930 1,888,382 Heath Nov. 22, 1932 1,969,047 Smith Aug. '7, 1934 2,009,902 Osterstrom July 30, 1935 FOREIGN PATENTS Number Country Date 289,561 Great Britain May 1, 1928 499,836 France Nov. 29, 1919 

9. PROCESS FOR THE PRODUCTION OF A HIGH QUALITY MOTOR FUEL WHICH COMPRISES EMULSIFYING A HYDROCARBON FRACTION BOILING IN THE MOTOR FUEL BOILING RANGE WITH WATER CONTINING A SUITABLE EMULSIFYING AGENT, SUBJECTING THE RESULTING EMULSION TO AN ELEVATED TEMPERATURE WHEREBY GUM-FORMING COMPONENTS FORM HIGHER BOILING CONSTITUENTS, STEAM TREATING SAID EMULSION TO REMOVE OVERHEAD SAID HYDROCARBON FRACTION BOILING IN THE MOTOR FUEL BOILING RANGE, SEPARATING THE BOTTOMS CONTAINING SAID HIGHER BOILING CONSTITUENTS AND RECYCLING AT LEAST A PORTION OF THE BOTTOM TO FURTHER CONTACT ADDITIONAL HYDROCARBON FRACTIONS BOILING IN THE MOTOR FUEL BOILING RANGE. 